combination longwall

20 LETTERS · STARTS WITH C

combination longwall is a valid 20-letter word worth 29 points in Scrabble and 39 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

C3O1M3B3I1N1A1T1I1O1N1L1O1N1G2W4A1L1L1

3 + 1 + 3 + 3 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 0 + 1 + 1 + 1 + 2 + 4 + 1 + 1 + 1 =29 PTS

DOUBLE WORD → 58TRIPLE WORD → 87

MEANING

What does combination longwall mean?